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Three silver metal spacer rings with M42 threads in 7.5mm 12mm 30mm thicknesses

Celestron

Celestron M42 Spacer Ring Kit (7.5mm, 12mm, 30mm)

SKU CH-DY95-GX0R5

Three M42 spacer rings (7.5mm, 12mm, 30mm) adjust camera-to-telescope distance for correct back focus and sharp astro images

  • Achieve perfect focus with three precision spacer rings (7.5mm, 12mm, 30mm)
  • Maximize image quality by eliminating vignetting and aberrations through precise distance adjustment
  • Ensure compatibility with standard M42 threads on astrophotography cameras and telescopes
  • Customize your setup for ideal back focus distance across various configurations
  • Match required 25mm back focus using 7.5mm spacer with ZWO ASI 183 MC PRO camera

Astrophotography Back-Focus Adjustment

The Celestron M42 Spacer Ring Kit provides three precision rings measuring 7.5mm, 12mm, and 30mm. They thread into standard M42 connections to set the exact distance between a camera sensor and telescope optics. The kit suits astrophotographers using DSLR, CCD, or CMOS cameras who need to correct back-focus for sharp stars across the frame.

M42 Thread Compatibility Limits

Spacers only work where both camera adapter and telescope present M42 threads. They cannot bridge different thread standards or compensate for optical designs that require specific corrector elements beyond simple spacing. The 42mm thread pitch is fixed, so components with T2 or other metric threads will not mate directly without additional adapters not included here.

Replaces Improvised Spacer Stacks

This kit replaces makeshift stacks of generic washers or single-thickness rings that rarely match the required distance. The jump is worth it when your imaging train demands a precise figure such as the 25mm back-focus for a RASA 8 with a ZWO ASI 183 MC PRO camera, where the camera consumes 17.5mm and a 7.5mm ring completes the exact spacing.

Highlights

  • Achieve perfect focus with three precision spacer rings (7.5mm, 12mm, 30mm)
  • Maximize image quality by eliminating vignetting and aberrations through precise distance adjustment
  • Ensure compatibility with standard M42 threads on astrophotography cameras and telescopes
  • Customize your setup for ideal back focus distance across various configurations
  • Match required 25mm back focus using 7.5mm spacer with ZWO ASI 183 MC PRO camera

Specifications

No published specifications for this item yet.

Questions about this item

Which spacer-ring thickness do I need for my camera and telescope combination?

The kit includes 7.5 mm, 12 mm and 30 mm rings; choose the one that makes up the difference between your camera's back-focus consumption and the telescope's required back-focus distance.

What does the 25 mm back-focus figure mean when I attach this to my RASA 8?

It is the total sensor-to-optics spacing the RASA 8 needs; with a camera that uses 17.5 mm you add the 7.5 mm ring to reach the 25 mm target.

Will the M42 thread on these rings fit my T-ring and camera adapter?

Yes, the rings use standard M42 threads, matching the T-ring and T-adapter used with Celestron optical tubes and common astrophotography cameras.

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